It has hitherto occurred that fitting of the cap on the body of the gelatin hard capsule that have received drugs therein loosens and a gap is caused therebetween or the cap falls out, whereby the drugs received within the capsule leak or are substituted for other ones. In order to prevent the occurrence of such disadvantages or hold the drugs in a stable state, therefore, it has usually been employed to seal its coupling portion.
For that purpose, various measures have been taken such as sealing of the coupling portion with a tape, fitting of a convex ring formed on the one of the coupling portion in a concave ring formed on the other of the coupling portion and the like. However, every one of these measures was disadvantageous in that it required much trouble and was low in efficiency. Therefore instead of these measures, the measure has been utilized which comprises the steps of placing capsules in a coating pan, spraying thereon a mixed solution of water and a volatile organic solvent whose volume ratio to water is 75-80%, rotating said pan for stirring, thus sealing and thereafter drying. However, this measure is defective in that satisfactory sealing is attained with difficulty, small capsules Nos. 4-5 adhere to each other and are deformed by crushing, distortion and the like, and further its efficiency is deteriorated owing to batch-treatment.